subacute

Subacute is a medical term used to describe a time course that lies between acute and chronic. It refers to conditions or phases that are not sudden or severe enough to be considered acute, yet not prolonged enough to be labeled chronic. The term focuses on progression and duration rather than on the exact level of severity.

There is no universal, fixed duration for subacute states. In general usage, subacute descriptions cover periods longer than a typical acute illness but shorter than chronic disease, often cited as roughly two to twelve weeks, though the window can vary by specialty. In imaging or neurology, “subacute” may reference symptoms or findings that began days to weeks before evaluation.

Examples of subacute contexts include a cough that persists beyond the usual course of a viral infection, or a fracture that is healing beyond the initial acute phase but has not yet reached the chronic stage. The term has also appeared in historical medical literature to describe certain infections of intermediate pace, such as subacute bacterial endocarditis, though modern practice tends to use more specific diagnoses.

In clinical practice, identifying a subacute course helps guide prognosis and management. It supports decisions about the intensity and timing of investigations, treatment, rehabilitation, and follow-up, indicating that the condition is not acutely dangerous but requires monitoring and a plan that adapts to its intermediate trajectory.

See also: acute, chronic, progressive, transient.